The integration of mobile communication network and WLAN (Wireless Local Access Network) is required widely, and extremely concerned by domestic and overseas operators. The operators wish the users can access, through WLAN, the self-supported PS service domains, such as games, portal websites and so on.
3GPP R6 TS23.234 defined accessing the self-supported PS (Packet Switch) service domains through WLAN in the year of 2004. But in this scheme, the WiFi terminal needs to establish a specific tunnel with a packet data gateway, and the user needs to be authenticated twice at the beginning, including an authentication of the wireless access network and an authentication of the packet data gateway. In this way, the WiFi terminal needs to support the scheme of establishing tunnel with the packet data gateway, which increases the load of the WiFi terminal, and increases the cost of the WiFi terminal, and the operations of the WiFi terminal are complicated.